1. Field of the Invention
The present invention relates to a method and system for controlling a resume process in a computer unit capable of connecting with an expansion unit.
2. Description of the Related Art
Most of recent personal computers, in particular, battery-driven lap-top computers have a resume function. The resume function is a function of, when a system power source is turned on, instantaneously resuming an operation state of a computer system immediately before the system power source is turned off. Therefore, when the system power source is turned off, data is saved regardless of an operation by an operator, and when the system power source is turned on again, the computer system is started, a program is loaded, and so on.
In order to realize the resume function, in system firmware, when the power source switch is turned off, values of various registers of the computer system are stored in a backup memory, and then, the system power source is turned off. When the system power source is turned on, a process for resuming an operation state of the computer system immediately before the system power source is turned off is executed. Contents stored in the backup memory are backed up by, e.g., a battery. In most of such computers, the resume function can be set/reset by an operator.
A computer system of this type can be connected to an external or internal expansion unit. As expansion units, a memory card, an IC (integrated circuit) card, an HDD (hard disk drive), an FDD (floppy disk drive), a CRT (cathode ray tube) display, and the like are used. Assume that the system power source is turned off after an expansion unit is connected to a computer main body and the resume function is set. In this case, when the system power source is turned on again, the resume function cannot always reliably operate. This is because the expansion unit connected to the computer main body is not recognized in advance in the computer main body, and the system cannot be designed to, e.g., save data in this expansion unit. Assume that after the resume function is set without connecting an expansion unit to the computer main body, and the system power source is turned off, the expansion unit is then connected to the computer main body, and the system power source is turned on. In this case, since the system configuration is changed, data stored in a main memory or a backup memory may be broken, and whether or not the resume function can reliably operate cannot be guaranteed.
Thus, a demand has arisen for a computer which can generate a warning to an operator and can save data before data is broken when the resume function is operated in a state wherein whether or not the resume process can reliably operate is not guaranteed.